1. Field of the Invention
This invention relates to a suction-discharge device for fluids that can be used as a multiple purpose pump as well as a compressor, and more specifically, the invention relates to a suction-discharge device for fluids using a rotary valve capable of continuously sucking and discharging fluids without occurrence of pulsations.
2. Related Art
In the past, in the vacuum pump which exhausts and reduces in pressure in the device, during the reciprocation of a piston, when pushing, pressure buildups while when pulling, pressure does not buildup, thus resulting in a drawback in which pulsations are violently generated.
Further, in a conventional high pressure pump used as a boiler feed water pump or the like, a piston is used for a pump (a plunger pump), thus likewise resulting in a drawback in which outlet pressure buildups pulsations. Because of such pulsations as described, a pointer of a pressure gauge for measuring outlet pressure oscillates up and down, and therefore, presently, a damage preventive means is mounted on the pressure gauge.
For solving such problems as noted above, the present applicant has developed a suction-discharge device for fluids capable of continuously ducking and continuously discharging fluids without substantially bringing about pulsations, and has filed for a patent application previously (Japanese Patent Application No. 20001-117455).
The aforementioned suction-discharge device (a rotary piston pump) was extremely epochal in that a fixed flow rate of fluids can be sucked and discharged continuously without substantially bringing about pulsations by rotation of a rotary valve.
However, in the aforementioned suction-discharge device, when an inner valve rotates from 0xc2x0 to 180xc2x0, the size of an opening becomes large gradually till 90xc2x0, and thereafter becomes small gradually, as shown in FIG. 1, and therefore, an outlet waveform is an crown sine curve as shown in FIG. 1, thus posing a problem that pulsations are brought about. It is noted that if two devices are used, and rotated with 90xc2x0 deviated, it is possible to always suck a fixed quantity and discharge a fixed quantity, thus enabling prevention of pulsations.
It is an object of this invention to provide a suction-discharge device for fluids capable of, without substantially bringing about pulsations even one unit, sucking continuously and discharging continuously under fixed flow rate and pressure.
It is a further object of this invention to provide a suction-discharge device for fluids in which a fluid quantity to be sucked and discharged is made to be fixed.
It is another object of this invention to provide a suction-discharge device for fluids capable of eliminating leakage of fluids almost completely.
For achieving the aforementioned objects, according to this invention, there is provided a suction-discharge device for fluids, comprising an inner tube fitted rotatably in a fitting hole of a device body, a cylinder fitted slidably in said inner tube, and a plurality of through-holes formed in said inner tube, wherein when one of the through-holes of said inner tube comes into communication with a suction hole of said device body, the other through-hole of the inner tube comes into communication with a discharge hole of said device body, and when a fluid is sucked from the suction hole communicated, the fluid is discharged from the discharge hole communicated, through-hole of said inner tube being formed into a slot which is long in a rotational direction and inclined, the suction hole and the discharge hole of said device body being formed into a slot to be crossed with said through-hole.
In short, the present invention has found out that the cause that if a normal slot is formed, a quantity of fluids to be sucked and discharged indicates a sine curve results from the fact that an opening of a suction port and a discharged port communicated indicates a sine curve, and provides the subject matter that the suction hole and the discharge hole communicated are made to be the fixed size always to thereby eliminate pulsations substantially.
Preferably, the through-hole of the inner tube, and the suction hole and the discharge hole of the device body may be formed so that the suction hole and the discharge hole communicated are moved in a moving direction of the cylinder.
Preferably, the plurality of through-holes of the inner tube, and the suction hole and the discharge hole of the device body in contact with the through-hole have the same shape and same size, and are inclined from 30xc2x0 to 60xc2x0, particularly, approximately 45xc2x0.
Preferably, a plurality of sets, each set of which comprises a suction hole and a discharge hole of the device body, are formed, and the set of a suction hole and a discharge hole may be communicated with the same through-hole of the inner tube and inclined in the same direction.
Preferably, with respect to the set of a suction hole and a discharge hole of the device body, the other is positioned at a position rotated by 180xc2x0 of the inner tube from one.
Preferably, the cylinder is reciprocated in association with the rotation of the inner tube.
The device body will suffice to have a fitting hole, and is not particularly limited, but generally, a block body having an outer tube or a fitting hole is used.
Preferably, the through-hole of the inner tube is formed to be inclined in the same direction to surfaces opposite to each other (the other is positioned at a position rotated by 180xc2x0 of the inner tube from one) and both lengthwise sides at a position apart in the sliding direction of the cylinder.
Preferably, the circumferential length of the slot of the inner tube, and the suction hole and the discharge hole of the device body is formed to be an arched slot of approximately 90xc2x0.
The above and other objects and advantages of the invention will become more apparent from the following description.